1. Field of the Invention
The present invention relates to a diaphragm spring for a friction clutch comprising a ring-like body area and a plurality of spring tongues, that are arranged in a row in the circumferential direction and extend radially inward from the body area.
2. Description of the Related Art
These types of diaphragm springs are used in friction clutches, and they are usually actuated at the radially inner end of their spring tongues by a clutch-release mechanism, so that, as a result of the existing lever relationships and the support of the diaphragm spring against a housing arrangement of the friction clutch, the force being exerted by the diaphragm spring on a pressure plate can be released. Because the diaphragm springs are usually made out of spring steel and thus have a certain elastic deformability as an intrinsic characteristic, deformations in the area of the spring tongues occur during the clutch-release process. Work must therefore be performed during this process in opposition to the intrinsic pretension of the diaphragm spring. In cases where the release distance is defined, these deformation reduce the extent to which the area of the diaphragm spring which exerts force on the pressure plate can be lifted off the pressure plate.
It is therefore known that ribs can be created in the spring tongues of these types of diaphragm springs, which ribs are formed by stamping or shaping the spring steel blank, so that essentially radially oriented pleats or elevations are formed in the spring tongues. These ribs are limited in the radial direction to prevent them from interfering with the support of the spring against the housing arrangement or against the pressure plate arrangement.